Chapter 2-1 Wearable Bio and Chemical Sensors 授課老師：謝振榆教授 班級：碩光材一甲 學號：10476126 學生：林子振

INTRODUCTION Chemical and biochemical sensors have experienced tremendous growth in the past decade due to advances in material chemistry combined with the emergence of digital communication technologies and wireless sensor networks (WSNs) . Chemical sensors have a more complex mode of operation, compared to physical transducers, in that they must interact in some manner with specific molecular targets in the sample medium.

Chemical and Biochemical Sensors A chemical or biochemical sensor consists of a recognition element (receptor)coupled with a transduction element (Figure 1). Parameters of Interest In recent years, significant effort has been focused on sampling and analysis of alternative body fluids, such as interstitial fluid , tears , saliva , and sweat. Analysis of sweat loss and sweat composition can also offer valuable information regarding hydration status and electrolyte balance.Breath analysis can reveal a diverse signature of physiological processes that occur in the body. Tears are another body fluid in which many proteins and electrolytes are normally present. Temperature and pH of the wound are also recognized to be critical for healing.

Figure 1: Schematic representation of the working principle of a chemical (biochemical) sensor. Some details of a real sensor are indicated. As an example, a filter or membrane may be used to separate the analyte to be detected from the interfering particles.

SYSTEM DESIGN This section focuses on the components of a wearable chemical or biochemical sensor system. A sample, either a body fluid or a gas, must be collected and delivered in the first instance. Then a suitable sensing mechanism must be integrated within the sensing platform also incorporating associated electronics and power supply. This overall system must be designed so that it can be placed on the body in a suitable location for long-term use in a reliable and comfortable manner.

Sample Handling Transport of Fluids in a Textile These wearable sensors were mainly developed for single-use applications since integration of textile bio-chemical sensors into clothes that can be used multiple times and for long periods of time is still very challenging.

Microneedle Technology Microneedle arrays offer a minimally invasive means of biosensing through highly integrated biocompatible devices. Sampling Gases Gas sensors may be employed to monitor the air surrounding the wearer (e.g., to detect dangerous levels of toxic gases). Delivery of the gas sample to the sensing surface can be controlled by choosing a fabric of suitable permeability to encase the sensor.

Types of Sensors Wearable Colorimetric Sensing Platforms Colorimetric sensors involve a color change at the active sensor surface, which can then be measured using optical techniques. Electrochemical Electrochemical sensors involve using electrodes to measure the electrochemical changes that occur when chemicals interact with a sensing surface.

CHALLENGES IN CHEMICAL BIOCHEMICAL SENSING Sensor Stability Ideally, a wearable sensor should be autonomous and reliable over time. Interface with the Body

Textile Integration Power Requirements Low-power device performance should be the first priority through smart integration and miniaturization of the electronic components. To power these devices using lightweight, comfortable components, flexible batteries, energy harvesting methods, or remote charging may be considered. Energy-harvesting feasibility depends mainly on four factors: the typical power consumption of the device; the use pattern; the device size (and thus the acceptable harvester size).

APPLICATION AREAS Personal Health Sports Performance Wearable sensors are applicable for all stages of treatment in healthcare, including prevention, immediate care, rehabilitation, and long-term support. In terms of market statistics, the biggest market is for sensors that can “sense” and “monitor” key diagnostic and therapeutic markers. Sports Performance Physiological monitoring has helped our understanding of the body and its response to exercise, and through physiological measurement individual training regimes can be planned and optimized. Safety and Security There are many scenarios in which personal safety could be supported through the use of wearable sensors for continuous monitoring of external hazards.

CONCLUSIONS In an innocuous manner that does not interfere with the daily routines of wearers. The wearer can be kept informed of his/her well-being in a dynamic manner, and individuals can become actively involved in the management of their personal health, making pHealth (pervasive health) a feasible goal. The other main application area of wearable chemical and biochemical sensors is in personal safety in warning of hazardous chemicals in the environment, which is of particular importance to first responders in disaster situations, and those involved in security and safety.

THE END Thank you for your attention.